Comparative assessment of total polyphenols, antioxidant and antimicrobial activity of different tea varieties of Bangladesh

Objective: To determine the total polyphenol content, antioxidant activity and antibacterial properties of the extracts of different Bangladeshi tea varieties such as flowery broken orange pekoe, broken orange pekoe, red dust and green tea.Methods: Total phenolic and flavonoid contents were determined by Folin–Ciocalteu and aluminum chloride colorimetric assay, respectively.The antioxidant capacity was determined by ferric ion reducing antioxidant power and phosphomolybdenum method.Antibacterial activity was evaluated by disc diffusion method in agar plate and subsequently, the minimum inhibitory concentration was determined by broth dilution method.Results: Total phenolic and flavonoid contents were significantly higher(P < 0.05) in green tea compared to other three black tea varieties.The green tea also showed a higher free radical scavenging and antioxidant activities than all the other tea varieties tested(P < 0.05).In addition, the extracts of all four tea varieties showed inhibitory activity against several pathogenic bacteria and also the same trend of higher antimicrobial activity of green tea than other tea varieties was observed.Conclusions: Taken together, the results of this study demonstrated that Bangladeshi tea,especially the green tea, may act as a substitute for natural antioxidants and as a promising antibacterial agent for beneficial influence in human health.

Phenolic Contents and Antioxidant Activities of Green Tea with and without Lemon

Tea is the most widely consumed beverage throughout the world, after water and is considered as a good antioxidant nutrient against free radical reactions. Lemons are citrus fruits that are very common in many parts of the world and are well known for their health benefits. In this study, different assays were used to evaluate total phenolic content and antioxidant activities of green tea with and without lemon. Our results showed that green tea with lemon has higher phenolic content, stronger reducing power than green tea without lemon;and exhibits a significant inhibition of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2). However, both samples exhibited high ferrous chelating activity with no significant difference among each other indicating a good antioxidant potential for both. This is a comparative study between green tea and green tea supplemented with lemon. The study contributes to a better understanding about how the addition of supplements like lemon might influence the antioxidant activity of tea.

Synergistic antioxidant interactions between green tea and Ocimum gratissimum

Objective: To evaluate the antioxidant interactions between aqueous infusions of green tea and Ocimum gratissimum at different ratios. Methods: Antioxidant activities of aqueous infusion of green tea and Ocimum gratissimum (leaves) alone or in combination at various proportions (3:1, 2:1, 1:1, 1:2, 1:3) were determined by DPPH, ABTS, NO and ex-vivo assays including lipid peroxidation and haemolysis. Total phenolic content and flavonoid content was calculated by Folin-Ciocalteu reagent and aluminum chloride colorimetry method, respectively. A correlation study was also conducted between the antioxidant activity and total phenolic/flavonoid content of various infusions. The interactions were analyzed by combination index applying CompuSyn software. Results: Green tea exhibited high radical scavenging ability as compared to Ocimum gratissimum infusion. Combination of green tea and Ocimum gratissimum exhibited moderate antagonism to strong synergistic interaction at various ratios. A strong correlation was found between total phenolic content/total flavonoid content and antioxidant activities of individual infusions (green tea and Ocimum gratissimum). For binary mixture at different ratios, a weak to strong correlation was observed between total phenolic content and antioxidant activity and almost no correlation between total flavonoid content and antioxidant potential. Conclusions: Overall, green tea and Ocimum gratissimum combination (1:1) displayed the highest antioxidant potential and maximum synergism.

Antihyperglycemic Activity of Moringa oleifera Lam Leaf Functional Tea in Rat Models and Human Subjects

Maintenance of glycemic control is important in preventing diabetes and its associated complications. Considering the current recommended approach for the use of functional foods and their bioactive components in the prevention and management of diabetes, the aim of this study was to determine the antihyperglycemic effect of Moringa oleifera functional tea in rat models and in normoglycemic human volunteers using the oral glucose tolerance test (OGTT). Moringa tea prepared by extracting Moringa leaf powder in distilled water (1:20 mg/ml) at 97°C for 30 min was administered at different doses to male Wistar rats and human volunteers prior to glucose loading. Blood glucose was measured at intervals of 30 min for 150 min. Consumption of Moringa tea prior to glucose loading suppressed the elevation in blood glucose in all cases compared to controls that did not receive the tea initially. The degree and pattern of decrease however, were dose dependent. In rats, intermediate doses of 20 ml/kg BW were more effective in reducing blood glucose overall (18.2%) vs 13.3% and 6% at doses of 10 and 30 ml/kg BW respectively. In humans, the final decrease in blood glucose was not significantly different for high 400 ml (19%) and low 200 ml (17%) doses. Of interest here was the pattern of decrease, being significantly higher (p < 0.05) at 30 min with 200 ml (22.8%) than with 400 ml (17.9%). It is suggested that low doses exert their antihyperglycemic effect more at intestinal level by inhibiting glucose absorption, whereas high doses exert their effect more in circulation. We conclude that Moringa oleifera tea has potential as a functional food in the management of hyperglycemia.

不同酚类成分及其组合对P.aeruginosa PAO1的抑制效果研究

为研究茶叶酚类成分及其复方对P.aeruginosa PAO1的体外抑制作用,筛选出用药量最低的最佳抑菌组方,采用倍比稀释法结合刃天青显色测定5种酚类成分对P.aeruginosa PAO1的最小抑菌浓度(MIC),并采用响应面法研究对P.aeruginosa PAO1具有较强抑制作用的最佳配伍。结果表明5种酚类成分对P.aeruginosa PAO1均有不同程度的抑制作用,5种茶叶活性成分对P.aeruginosa PAO1的抑菌性大小为:EGCG>TF60=ECG>EGC>EC。响应面分析结果表明,EGCG、EGC、ECG、TF60这4种酚类成分以1.0∶4.0∶4.81∶4.0的比例配伍时对P.aeruginosa PAO1具有最佳抑菌效果。

Comparative Study of the Antioxidant Activity of Two Popular Green Tea Beverages Available in the Local Market of Saudi Arabia

Antioxidants have numerous applications due to their multiple roles in diminishing harmful effects of oxidative stress. The objective of this work was to highlight the importance of green tea by evaluating the antioxidant activity of the most popular green tea brands in Saudi Arabia, Lipton and Rabea. To our knowledge, no studies have so far been done to estimate the antioxidant activity of these brands. To determine the antioxidant activities of these two brands, 10 mg/ml of each brand was extracted and their total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, hydrogen peroxide scavenging activity, ferric reducing power and ferrous ion chelating effect were measured. The TPC of Lipton tea was 678.7 υg of gallic acid equivalents (GAE)/10mg, whereas in Rabea tea, the TPC was 647.1 υg GAE/10mg. The presence study indicated that there were no significant differences in total phenolic contents and the percentage inhibition as shown in DPPH and H2O2 assays among Lipton and Rabea green teas. Moreover, it was found that all assays have exhibited high antioxidant activity in both green teas. In conclusion, our study showed evidence for evenness and stability of the antioxidant activity of the two commercial green teas available in the markets of Saudi Arabia. Continued researches are needed to further the current knowledge on the health-promoting effects of this popular beverage using different supplements by different mechanisms.

11种凤凰单丛茶中9种黄酮酚类物质的检测方法建立与分析

建立了高效液相色谱法(HPLC)同时测定凤凰单丛茶中9种黄酮酚类物质的检测方法。采用色谱柱Waters Xterra■MS C18(4.6 mm×250 mm,5μm),以乙腈和0.02%乙酸为流动相进行梯度洗脱,流速1.0 mL/min,柱温25℃,二极管阵列检测器280 nm波长检测,外标法定量。结果表明,9种黄酮酚类物质中香豆酸、绿原酸、儿茶素、芦丁和槲皮素在0.01~0.20 mg/mL,木犀草素、金丝桃苷、山奈酚和槲皮苷在0.025~0.250 mg/mL线性关系良好,相关系数(r)均大于0.999;方法检出限为0.2~1.8μg/g,定量下限为0.6~5.9μg/g。在25μg/g和250μg/g两个加标水平下,9种黄酮酚类物质的平均回收率为95.4%~104.8%,相对标准偏差RSD(n=6)均小于5%。该方法操作简便、快速、准确,适合于黄酮酚类物质的定性与定量检测。

不同成熟度老鹰茶中酚类化合物含量及抗氧化活性研究

为了探究两种不同成熟度老鹰茶中酚类化合物含量及抗氧化活性的差异,以对其进行辨识及质量评价,该研究利用液相色谱-串联质谱(LC-MS/MS)法测定老鹰茶中15种酚类化合物,采用DPPH自由基清除率、ABTS^(+)自由基清除率、Fe^(3+)还原能力评价两种茶叶抗氧化能力,再通过数据统计分析探讨两种老鹰茶酚类化合物含量及抗氧化活性的差异,并进一步探索老鹰茶中不同酚类化合物对于抗氧化的贡献。结果表明:(1)嫩叶茶中儿茶素、对香豆酸、异槲皮苷、金丝桃苷、烟花苷、紫云英苷、山奈酚、槲皮素、阿福豆苷含量显著高于老叶茶,其中儿茶素、异槲皮苷、紫云英苷平均含量比老叶茶分别高1039.43、169.12、257.35 mg·100 g^(-1)。聚类分析(HCA)、主成分分析(PCA)、正交偏最小二乘判别分析(OPLS-DA)均可将二者区分。(2)方差分析(ANOVA)结果显示在抗氧化能力上,二者在DPPH自由基清除率、ABTS^(+)自由基清除率、Fe^(3+)还原能力之间具有显著性差异,嫩叶茶优于老叶茶。(3)偏最小二乘回归分析(PLSR)法提示老鹰茶中的异槲皮苷、儿茶素、紫云英苷、绿原酸、金丝桃苷、对香豆酸、山奈酚是其发挥抗氧化效能的主要酚类化合物。该研究结果可为老鹰茶的质量控制及应用推广提供一定的参考。

五指山野生大叶茶叶片代谢物鉴定和特征分析

为了解五指山野生大叶茶(Camellia sinensis var. assamica)代谢物的特征,利用代谢组学方法,对采集自五指山地区的野生茶树和人工茶园茶叶的代谢物成分开展了比较研究,在野生茶树茶叶中鉴定得到398个含量显著上调的代谢物和247个显著下调的代谢物。基于偏最小二乘法判别分析表明,野生茶叶和人工茶叶分别聚为一类。富集分析结果显示,野生茶树叶片中含量显著上升的代谢物的功能主要富集于糖酵解、丙酮酸合成、氨基糖代谢和核苷糖代谢等糖代谢通路,以及酚类物质合成、核黄素代谢、鞘磷脂代谢和黄酮合成等通路,而显著下降的代谢物的功能主要富集于氨基酸代谢和油脂代谢等初生代谢。

普洱茶的抗氧化酚类化学成分的研究

从云南省双江县勐库产的普洱茶中分离得到11个化合物，分别为：（-）-没食子儿茶索（GC，1），（-）-表儿茶素（EC，2），（＋）-儿茶素（C，3），杨梅素（4），没食子酸（5），山奈酚（6），山奈酚-3-O-B-D-葡萄糖甙（7），山奈酚-3-O-P丁糖甙（8），槲皮素（9），槲皮素-3-O-B-D葡萄糖甙（10）以及2，5-二羟基苯甲酸（11）。其中，化合物6-11为首次从普洱茶中分离得到。DPPH自由基清除活性测试结果表明，化合物2、3、5的活性与阳性对照品抗坏血酸接近。化合物的结构与其活性的关系比较分析表明，简单儿茶素（2，3）和简单酚类化合物（5）的抗氧化活性较高，与阳性对照品抗坏血酸接近；黄酮类化合物（4，6，9）次之，黄酮类配糖体（7，8，10）及化合物11则较差。

茶多酚在体外诱导HL-60细胞的凋亡

目的：寻找新的肿瘤细胞凋亡诱导剂。方法：选用茶的主要活性成分茶多酚，采用噻唑蓝（ＭＴＴ）还原法，ＤＮＡ凝胶电泳以及透射电镜技术，在体外观察了茶多酚对人急性早幼粒白血病细胞（ＨＬ－６０）凋亡的影响。结果：被２５０ｍｇ／Ｌ茶多酚作用５ｈ后ＨＬ－６０细胞进行凝胶电泳呈现出典型的ＤＮＡ条带，透射电镜下看到凋亡小体，茶多酚对ＨＬ－６０细胞凋亡的诱导活性平行于它的细胞杀伤作用。结论：在体外培养条件下。

茶多酚清除自由基和抗氧化作用的研究

本文用化学发光法和TBA法测定了GTP对不同反应体系产生的氧自由基的清除作用,结果表明,GTP对X/XO和PMA刺激的PMN体系中产生的化学发光强度的清除作用均有量效关系,GTP对PMA刺激的PMN和红细胞膜体系在TBA反应中产生的MDA的抑制作用亦均有量效关系。

红曲茶黄酒多酚色谱分析及其对小鼠抗氧化酶活力影响

该研究将绿茶加入红曲黄酒中,采用高效液相色谱(HPLC)法检测红曲茶黄酒酚类物质含量,酶联免疫吸附测定(ELISA)试剂盒法检测小鼠血清的抗氧化酶活力及丙二醛(MDA)含量,并以传统工艺红曲黄酒对照,考察添加绿茶共发酵对红曲黄酒酚类物质及小鼠体内抗氧化酶活力的影响。结果表明,添加绿茶共发酵可使红曲黄酒新增4种绿茶特征酚类物质和咖啡因,儿茶素、绿原酸、没食子酸及总酚含量分别提高27.38%、29.52%、30.77%和37.69%;与传统红曲黄酒相比,小鼠血清的超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)酶活力分别显著提高3.05%、12.50%(P<0.05),MDA含量显著降低2.98%(P<0.05)。添加绿茶共发酵不仅可丰富传统红曲黄酒的酚类物质组分及含量,还可提高传统红曲黄酒的抗氧化能力。

遮荫对不同季节茶树新梢的内含成分影响研究

对福鼎大白茶园进行不同遮荫方式处理,并用冷冻干燥对鲜叶固样,分析其主要的化学成分。结果表明:遮荫能使夏秋茶的多酚类、粗纤维含量减少,酚氨比下降;氨基酸、咖啡碱、叶绿素含量增加。不同季节遮荫效果不一样,春季遮荫效果不明显,夏季效果最好,秋季次之;不同遮荫方式的遮荫效果也不一样,以黑色双层遮阳网遮荫效果最好。

20种市售凉茶类植物饮料抗氧化性的比较研究

利用DPPH自由基清除实验、ORAC法和Fe3+还原能力实验,考察20种市售凉茶类植物饮料的抗氧化性。结果表明:20种凉茶在不同的抗氧化评价体系中均表现出不同程度的抗氧化能力。运用模糊评价理论建立的抗氧化综合评价模型表明,抗氧化综合评价值最高的5种凉茶类植物饮料皆为传统凉茶铺出售的凉茶。各凉茶试样的抗氧化综合评价值与总酚含量有一定的相关性,但线性关系不显著。

口服绿茶多酚对离体心脏的保护作用

目的:探讨口服绿茶多酚对离体心脏的保护作用。方法:16只SD大鼠,随机分为两组,实验组每天经胃管灌服5%绿茶多酚溶液40mL,对照组灌服生理盐水,20d后分别摘取心脏行离体灌注(Langendorff模型),测定心功能,然后灌注并保存于4℃UW保存液中,8h后取出,再行Langendorff灌注,再次测定心功能参数。测定再灌注后冠脉流出液中的乳酸脱氢酶(LDH)、肌酸激酶(CK)活性,心肌组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量;观察心肌超微结构。结果:除心率外,实验组各项心功能参数均优于对照组(P<0.05),心肌含水量、MDA低于对照组(P<0.05),冠脉流出量、心肌组织中SOD活性优于对照组(P<0.05),冠脉流出液中LDH、CK活性低于对照组(P<0.05);实验组心肌超微结构的损伤较对照组显著减轻。结论:口服绿茶多酚对大鼠离体心脏具有保护作用。

紫娟茶提取物对血管紧张素转换酶、α-淀粉酶和胰脂肪酶的体外抑制作用

目的:探究紫娟茶提取物是否具有一定潜在的降血压、降血糖和减肥功效,并分析紫娟茶提取物中茶多酚和花色苷在其中起到的作用。方法:对紫娟茶进行提取,将紫娟茶粗提物(ZTE_1)再分离为花色苷的粗提物(ZTE_2)与茶多酚的粗提物(ZTE_3),将ZTE_2进一步纯化分离出两种纯化花色苷——飞燕草-3-O-β-D-(6-(E)-对香豆酸)吡喃半乳糖苷(delphinidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside,AN_3)和矢车菊-3-O-β-D-(6-(E)-对香豆酸)吡喃半乳糖苷(cyanidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside,AN_4);分别评价ZTE_1、ZTE_2、ZTE_3、AN_3和AN_4对血管紧张素转换酶(Angiotensin converting enzyme,ACE)、α-淀粉酶和胰脂肪酶的体外抑制作用,并与表没食子儿茶素没食子酸酯(Epigallocatechin gallate,EGCG)进行比较,评价了AN3和AN4对三种酶的抑制类型。结果:ZTE1、ZTE2、ZTE3、AN3和AN4对三种酶均有一定的抑制作用,粗提取物中,ZTE3对三种酶、ZTE1对α-淀粉酶和胰脂肪酶、ZTE2对α-淀粉酶的抑制超过或相当于EGCG的效果,其中ZTE3对ACE、ZTE2对α-淀粉酶、ZTE1对胰脂肪酶的抑制效果最强;纯化花色苷中,AN3对α-淀粉酶的抑制效果较好,与EGCG无显著性差异,AN3对三种酶的抑制效果均优于AN4;此外,AN3和AN4对三种酶均为非竞争性抑制,抑制常数Ki分别为:0.33、0.37 mmol/L;0.39、0.41 mg/m L;0.22、0.78 mg/m L。结论:紫娟茶对高血压、高血糖和肥胖症有一定的潜在功效。

茶叶添加方式对酿造啤酒理化特性及感官品质的影响

在啤酒酿造工艺的煮沸和主发酵阶段分别添加乌龙茶,探讨茶叶不同添加方式对啤酒理化特性、抗氧化能力、啤酒贮存稳定性以及感官特性的影响。结果显示,与未添加茶叶的啤酒产品(对照组CG)相比,在煮沸阶段(煮沸添加组BG)和主发酵阶段(主发酵添加组MG)分别添加0.3g/L的茶叶均提高了酵母发酵速率;添加茶叶的两个茶啤酒产品(煮沸添加组和主发酵添加组)的DPPH自由基清除能力分别提升至82.74%和89.21%、ABTS+自由基清除能力分别提升至41.53%和51.49%、铁离子还原能力分别提升至36.49和43.83 mg/L,且成品茶啤酒贮藏期间的抗老化能力提高;茶啤酒中总酚以及儿茶素(EGC、C、EGCG、EC、GCG、ECG)和咖啡碱(CAF)含量升高,其中,主发酵添加组茶啤酒样品总酚和EGCG含量显著高于对照组和煮沸添加组啤酒(P<0.05),分别达到734.40和8.43 mg/L。进一步的感官品评结果显示添加茶叶提高了啤酒产品的茶香气和茶滋味,其中主发酵添加组啤酒的茶香气、茶滋味及酒体协调性最好。由此可知,在啤酒酿造工艺中添加茶叶提高了酵母发酵速率,增强了啤酒中酚类物质含量及其抗氧化和抗老化性能,同时也为啤酒增添了新的茶风味产品。

茶多酚对哮喘大鼠气道炎症和气道重塑的干预研究

目的:研究茶多酚(TP)对支气管哮喘大鼠早期和晚期气道氧化应激水平及气道炎症、气道重塑的影响。方法:48只大鼠随机分对照组、哮喘组、早布地奈德(BUD)组、晚BUD组、早TP组和晚TP组,每组8只。早BUD组、早TP组在造模前2周药物干预,晚BUD组、晚TP组在造模5周后药物干预。造模12周时观察各项指标。测定支气管壁的平滑肌面积、胶原沉积面积,以及肺组织转化生长因子-β1(TGF-β1)的表达。测定肺组织TGF-β1含量、丙二醛(MDA)含量及超氧化物歧化酶(SOD)活力。结果:早TP组、晚TP组、早BUD组干预后支气管壁平滑肌面积、胶原沉积面积和TGF-β1含量较哮喘组均有改善(P<0.05或P<0.01)。晚BUD组较哮喘组无明显改善(P>0.05)。哮喘组肺组织中MDA含量明显上升,SOD活性显著下降,与对照组比较差异有统计学意义(P<0.01);各药物干预后SOD活性均上升,MDA含量均下降,以早TP组最明显(P<0.01)。SOD活性与MDA含量呈负相关,TGF-β1含量与MDA含量呈正相关。结论:茶多酚可能通过清除氧自由基,减少气道炎症及氧化应激,从而改善或延缓气道重塑的发生。

茶多酚-木糖醇漱口液抑制菌斑形成的体内研究

目的 研究茶多酚 -木糖醇漱口液在体内对菌斑的抑制作用。 方法 采用双盲、自身前后对照实验研究茶多酚与木糖醇联合应用的菌斑抑制能力 ,并与单独使用茶多酚、木糖醇以及口泰漱口液的效果进行比较分析。 结果 茶多酚 -木糖醇漱口液对菌斑的抑制作用与口泰相比差异无显著性 ,较单独使用茶多酚或木糖醇时为强 ,且能使漱口液的口感明显获得改善。 结论 茶多酚和木糖醇在抑制菌斑形成的过程中可能存在协同作用 。